Any recent history of oral sex? It looks like there is a sore just above the uvula.
I’d say he should get that sore cultured. It could just be Herpes Simplex Virus (HSV), which you can get just from kissing someone with an active infection. In that case, acyclovir would help prevent a future outbreak. Another possibility is cytomegalovirus (CMV), also transmittable via kissing.